Luteijn, Maartje, Mahboubi, Hicham, Trojer, Dominic, Handl, Cornelia, Pizzato, Nicolas, Pfeifer, Martin, Voshol, Johannes, Giorgetti, Elisa, Manneville, Carole, Garnier, Isabelle, Mueller, Matthias, Zeng, Fanning, Buntin, Kathrin, Markwalder, Roger, Schroeder, Harald, Weiler, Jan, Khar, Dora, Schuhmann, Tim, Groot Kormelink, Paul, Gubser Keller, Caroline, Farmer, Pierre, Mackay, Angela, Beibel, Martin, Roma, Guglielmo, D'Ario, Giovanni, Merkl, Claudia, Schebesta, Michael, Hild, Marc, Elwood, Fiona, Ripin, Nina, Chery, Antoine, Allain, Frederic, Labow, Mark, Gabriel, Daniela, Nash, Mark, Hunziker, Juerg and Meisner Kober, Nicole-Claudia (2025) Chemical manipulation of RNA foci mobilizes G4C2 repeat RNA from nuclear storage foci for translation into dipeptide repeat polyproteins in C9Orf72 ALS neurons. Nucleic acids research, 53 (7). pp. 1-28. ISSN 1362-4962; 0305-1048

Abstract

An intronic G4C2 repeat expansion in the C9orf72 gene is the major known cause for Amyotrophic Lateral Sclerosis(ALS). The disease mechanism is still not fully understood,but a pathological gain of function of nuclear repeat RNA foci as well as translation into toxic dipeptide repeat (DPR) polyproteins have been proposed. We screened 100,000 small molecules in C9orf72 patient iPS derived neurons for modulation of RNA foci and identified analogs of known spliceosomal modulators
targeting SF3B1. These compounds trigger elimination of RNA foci post-transcriptionally, independent of C9orf72 pre-RNA splicing and gene context. This changes the interactome of RNA binding proteins bound to the G4C2 repeat RNA with a strongly enhanced binding of the splice and nuclear export factor SRSF1. As a result, the repeat RNA is licensed into RAN translation in the cytoplasm, thereby enhancing DPR cell toxicity. In turn, trapping SRSF1 in the cytoplasm by small molecule inhibition of SRPK resulted in build of nuclear RNA foci. These data suggest a protective rather than toxic role of
nuclear RNA foci and provide the first set of orthogonal pharmacological tools to study C9orf72 repeat RNA metabolism and ALS pathobiology.

Item Type:	Article
Keywords:	ALS, C9orf72, splicing, SF3B1, spliceostatin, SRSF1
Date Deposited:	06 May 2025 00:45
Last Modified:	06 May 2025 00:45
URI:	https://oak.novartis.com/id/eprint/43462